In this paper, we proposed the process of the diaphragm for miniaturizing MEMS capacitive pressure sensor and controlling its sensitivity. We fabricated micro diaphragm using a Ru₆₅Zr₃₀Al₅(at.%) thin film metallic glass (TFMG). The as-sputtered TFMG on Si substrate were annealed at 315-440°C for 5 minutes in vacuum. After annealing, micro diaphragms were fabricated by an etching Si substrate using a reactive ion etching system. Although the diaphragm without annealing had dome structure, the diaphragm annealed above 340°C formed a flat structure. The deflection of the diaphragm against applied pressure depended on the annealing temperature and decreased at higher temperatures. The pressure sensor was modeled using this diaphragms. The pressure measurement range and sensitivity were 250 Pa and 6.4×10^-3 pF/Pa, respectively, for annealed at 340°C, and 1800 Pa, and 8.1 × 10^-4 pF/Pa, respectively for annealed at 440°C.